The Bush administration’s plan to make a war with Iraq seem inevitable continued last week with its descriptions of the number of ground troops needed and potential hosts of needed air bases. But the questions Congress should be asking go beyond the logistics of war into what a war on terrorism means and how a sustained U.S. presence internationally will be carried out.

No one doubts Saddam Hussein falls into the “evil-doer” category – his unconscionable attack on the Kurds alone qualifies him. But the pretext for an attack by the United States is that Iraq has refused to submit to high-level inspections for weapons of mass destruction. But stiffing the international community seems like a thin reason for a full-scale invasion. The United States has ignored demands from the United Nations more than once and received nothing worse than an insider-politics scolding. The public case for attacking Saddam Hussein should be based on evidence that these weapons exist and there are credible reports that he plans to use them imminently.

European allies generally dislike the idea of invading Iraq, and they point to events such as the recent agreement among Arab nations that if one is attacked, they will all consider themselves attacked and the lack of an organized oppositions to take over should Saddam Hussein be killed or captured as reasons for staying away. The sincerity of the unity pledge will be confirmed or refuted by which nations allow the United States air rights or base support and so could be known ahead of time. But the second concern, of what comes after, seems legitimate and suggests that under the best of circumstances the Bush administration would be busy nation-building as few administrations have done in the last quarter-century. Finding and supporting a stable, nonaggressive replacement government that will ensure the continued supply of oil from the Middle East could take quite a while and cost plenty.

This possibility should especially interest Congress, which has been loath to expand the U.S. foreign aid budget and reluctant to get involved even when clear catastrophes were occurring in places such as Bosnia. The Sept. 11 attacks show that an isolationist stance is impossible, but there is a difference between a military response to a terrible attack and an invasion to kill a long-standing enemy. Exactly how that difference shapes policy is a fitting subject for congressional debate.